Certain manufacturing operations lend themselves to performance by manually controlled industrial robots because of the hazardous nature of such operations. The hazards arise from the materials involved such as explosive, corrosive, pathogenic, cryogenic, radioactive or the like materials or from the necessity of performing such operations in atmospheres which are poisonous or non-life supporting to humans such as welding in inert gases or operations which require a vacuum. Other situations which benefit from manually controlled robotics include operations which are necessarily carried out by remote control such as some deep sea operations and outer space operations. While some such operations can be performed by automatically controlled robots with feedback loops for self-correction, others require direct human control.
The primary human feedback senses for manual activities are usually vision and touch or feel. Considerable effort has been expended in the development of remote controls which have a useful feel such that a given amount of manual movement of a control results in an expected result. A portion of the success of such a control involves learning to use the control by the operator.
The development of "remote sight" has, to an extent, lagged the development of remote manipulation because of the complexities of human vision and the complexities of the systems for aiding human vision, namely, television. Human vision is stereoscopic; that is, the right and left eyes sense slightly different images because of the lateral separation therebetween. The brain interprets the difference in image to derive depth perception such that a three dimensional visual sense results. Through practice as an individual ages, eye-hand coordination can become quite accurate.
Television has for the most part been a two dimensional medium, notwithstanding such techniques in color television as so-called "3D" effects wherein two of the component colors, such as red and green, are offset laterally and when viewed through a set of properly oriented red and green spectacle lenses gives an approximation of three dimensional vision. Such effects, while arguably adequate for applications as in motion pictures, do not convey an accurate enough sense of depth for such activities as the control of a robotic arm. In order to obtain a truer video image of the depth dimension, that is in the direction of the line of sight of a video camera, a second video camera which is laterally spaced or elevated from the first camera has been required. A viewer is then required to watch and coordinate the images on two separate viewing screens. The result is an improvement over two dimensional viewing, but does not provide the apparent simplicity and the convenience of natural vision.
In more recent years, image (video camera) tubes and picture tubes, or cathode ray tubes (CRT's), have been miniaturized to the extent that a pair of image tubes can be positioned to approximate the perspective of the human eyes; and a pair of CRT's can be positioned and the images projected preferably indirectly, to the eyes of a human such that a good approximation of natural stereoscopic vision can be achieved. Non-CRT visual display devices such a liquid crystal, light emitting diode, and fluorescent matrix displays are currently being applied to reduce the size of video displays even further.